期刊名称：AKCE International Journal of Graphs and Combinatorics
印刷版ISSN：0972-8600
出版年度：2019
卷号：16
期号：1
页码：66-77
DOI：10.1016/j.akcej.2018.07.002
语种：English
出版社：Elsevier
摘要：AbstractA toric arrangement is a finite collection of codimension-1 subtori in a torus. The intersections of these subtori stratify the ambient torus into faces of various dimensions. The incidence relations among these faces give rise to many interesting combinatorial problems. One such problem is to obtain a closed-form formula for the number of faces in terms of the intrinsic arrangement data. In this paper we focus on toric arrangements defined by crystallographic root systems. Such an arrangement is equipped with an action of the associated Weyl group. The main result is a formula that expresses the face numbers in terms of a sum of indices of certain subgroups of this Weyl group.
关键词：KeywordsToric arrangementsFace enumerationsf-vectorAffine Weyl groups
